Objective. Ultrasound scans have become a routine part of antenatal care. Recent developments have meant that ultrasound has gone beyond monitoring the pregnancy and diagnosis of major abnormalities. Its routine use now includes screening for subtle fetal abnormalities and indications of chromosomal abnormality. Unfortunately ultrasound screening for chromosomal abnormalities has a low positive predictive value (similar to maternal serum screening), and only about 2% of pregnancies identified as ‘high risk’ will be diagnosed with a chromosomal abnormality. The other 98% of ‘high risk’ results are termed ‘false positive’. The aim of this paper is to elucidate the range of subjective experiences of women in response to having these results. Method. The approach employed was interpretative phenomenological analysis. Semi-structured interviews were carried out with 24 pregnant women after ‘false positive’ ultrasound results. These were subjected to a qualitative analysis. Results. Participants perceived the ultrasound scan primarily as a social, non-medical event and were unprepared for the result the scan elicited. Two-thirds described residual feelings of anxiety even after normal diagnostic results were known, sometimes attributed to continued fears about fetal abnormality, but more often attributed to a generalized feeling that something else unexpected could happen to threaten the pregnancy. Conclusions. The paper has pointed to important discrepancies in the experiences of women undergoing ultrasound screening and the aims of informed choice. We would suggest consideration should be given to providing information on both the medical purposes of screening and on possible outcomes from it. The study also points to the possible need for counselling support for the majority of women who go on to receive confirmation of a negative diagnosis, counselling addressed at helping women to readjust to having a ‘low risk’ pregnancy.